In the prior art, aeration systems are well known for use in pneumatic trailer tanks, rail cars, storage tanks, and other containers. Such systems include aeration devices connected to pressurized air sources. The aeration devices which introduce air into the containers to aerate dry bulk materials, such as flour, sugar, starch, fertilizer, plastic resins, cement, fly-ash, and other particulate materials stored within the containers. Such prior art devices may include a flexible element which provides a seal when air pressure is terminated but permits passage of air from the device into the container when air pressure is initiated. An example of such device may be found in my U.S. Pat. No. 4,662,543, dated May 5, 1987.
U.S. Pat. No. 4,662,543 teaches an aeration device comprising a resilient flexible skirt which has an inner generally conical surface and an outer generally conical surface. An anchor stud and cup arrangement is provided for securing the skirt to an inside surface of a container wall with a base end of the skirt opposing the inside surface and with the anchor stud and cup arrangement drawing the skirt axially toward the wall to prestress the skirt. The skirt cooperates with the inside surface of the wall to define a pressure chamber. Means are provided for supplying a flow of pressurized air from a source external of the container to the pressure chamber. From the pressure chamber, the air passes under the base end of the flexible skirt and into the container to fluidize the bulk material.
Other aeration devices are known which include a flexible skirt mounted to a threaded stem with an internal air passageway in the stem as shown in FIG. 1A. In FIG. 1A, a flexible skirt 10a is mounted to a first end 12a of a stem 14a. Straight threads 16a are provided at an opposite end 18a of stem 14a on an exterior surface of the stem. The straight threads permit a threaded member, such as a nut 20a, to mount the stem to the container wall 22a. A flexible seal member 24a seals between the container wall 22a and stem 14a. An inner passageway 26a is defined in stem 14a for the passage of pressurized air from end 18a toward end 12a through air ports 28a. Internal taper pipe threads 30a are provided on stem 14a to permit interconnection of stem 14a to an appropriately sized threaded coupling extending from a source of pressurized air.
Several problems arise when mounting the aeration device of FIG. 1A to the container. A first problem relates to the connection of the aeration device to the container wall. If too large a hole is drilled in the container wall, the aeration device may become misaligned and the seal member may not seal properly. If the seal member does not provide a proper seal, the pressurized air may exit the container between the stem and the wall, instead of fluidizing the container contents.
Another problem related to mounting the aeration device of FIG. 1A to the container concerns the threaded interconnection of the aeration device to the pressurized air supply. Problems arise for aeration device manufacturers, aeration device suppliers, and/or aeration device installers when the aeration devices threadably interconnect to pressurized air supplies. Special emphasis must be placed on providing the appropriate threads on the aeration device to permit interconnection to the pressurized air supply provided. An example of two different thread types that may be encountered on the couplings extending from the pressurized air supplies are (1) American National Standard Taper Pipe Threads; and (2) British Standard Taper Pipe Threads. An appropriately threaded stem of the type in FIG. 1A needs to be provided to threadably mount to a fitting extending from the pressurized air supply. This can raise manufacturing costs if different parts are required to interconnect to differently threaded fittings. This can also result in a large inventory of different parts needing to be maintained by the supplier. It can also result in the installer having to use extra care when obtaining the appropriate parts for installing the aeration system.
A related installation problem concerns how the installer handles different air supplies of varying pressures and/or varying fittings. For example, the pressurized air supply may include a flexible tube or hose having a particular size. The installer has to mount the tube or hose to the aeration device. The installer is therefore concerned with how easily the connection can be made between the aeration device and the pressurized air supply.
There is a need in the art for aeration devices and methods which address the above concerns and other concerns.